This invention relates to low-power, particularly battery-operated, RF and IR transmitters.
Unlike infra-red (IR) transmitters which require a direct line-of-sight with their respective receivers, RF transmitters have the advantage that no such direct line-of-sight is required. On the other hand, IR transmitters are becoming increasingly popular owing to their small size and their ability to handle ever-increasing volumes of data traffic at high speed. Remote controls for television and the like based on IR detectors are, of course, well known but there is an increasing tendency to employ IR transmitters as personal data badges for a variety of applications. Such applications include access control utilities: not only for gaining access to protected territory but, no less importantly, for maintaining constant supervision and monitoring of a person""s location.
One specific application where such a requirement is mandatory elates to the monitoring of patients in a hospital. A patient is frequently instructed to present himself at one or more departments within the hospital for the purpose of various examinations such as, for example, X-rays, ultrasound and so on. During this routine, the patient is obviously unsupervised and generally makes his own way from one department to another. Notwithstanding that this procedure is common, it is fraught with danger and insecurity. There is the obvious risk that, owing to confusion on the part of the patient, he may go to the wrong department, thereby at best wasting significant amounts of time if not undergoing unnecessary tests. There is also the risk that the patient may leave the hospital without having had the necessary tests and that, in consequence, further diagnosis of the patient may be aborted with possibly catastrophic results.
The use of IR detectors for monitoring the whereabouts of moving people is known per se. Therefore, one possible solution to the scenario set out above would be to provide each patient with an IR identity tag, whereupon his progress throughout the hospital could be monitored. However, it is not uncommon for patients, unthinkingly, to put their identity badge inside a pocket or purse. In this case the patient is effectively xe2x80x9clostxe2x80x9d from view because the IR transmitter within the identity badge requires direct line of sight with the receiver and there is no way in which the IR signal can penetrate the patient""s pocket or purse. Obviously, should this occur, the patient""s apparent loss will immediately be inferred and steps may then be taken by the hospital""s security staff to locate him. However, this is a cumbersome procedure and increases the already overstretched burden of the hospital""s security staff. Moreover, of course, if the patient succeeds in leaving the boundaries of the hospital, then locating the patient in order to retrieve the missing badge becomes even more difficult; and if, moreover, the patient""s health suffers as a result, then the hospital may be held criminally negligent.
Similar considerations apply to the use of IR badges for tracking babies in order to prevent theft from maternity wards. In this case, it is also necessary to safeguard against a thief merely removing the IR badge prior to abduction. This may be achieved by typing the badge to the baby using an electrically conductive wire and then monitoring the electrical continuity of the wire.
A further drawback with the use of IR badges for location tracking is that accurate location is dependent on dividing an area into independent units each having an IR reader for communicating with an IR badge within its respective reception coverage. By such means, it is easy to determine which reader is in line of sight contact with a particular badge and thereby infer the location of the badge. This, however, has tended to militate against the use of IR badges for tracking location in wide open spaces.
There is thus clearly a need to allow for constant monitoring of a patient within a hospital in both confined and open spaces whilst, at the same time, protecting both the patient and the hospital management against his apparent disappearing owing to the mis-location of a conventional IR identity tag.
The use of an RF transmitter for this purpose would obviously go a long way to solving such a problem. However, RF transmitters are subject to problems of their own, including the need to secure approval by the requisite Communications Authority. Moreover, the use of an RF-only system for the purpose of location and identification is not feasible, because RF transmission crosses walls, ceilings and floors, thus militating against exact and precise determination (per room or enclosed area) of the location of the RF transmitter.
It is therefore an object of the invention to provide a low-powered RF transmitter in which the above-mentioned drawbacks are significantly reduced or eliminated.
It is a particular object of the invention to provide an RF transmitter for mounting in conjunction with an IR transceiver so as to allow for the data to be transmitted by RF as well as by IR within a single battery-operated portable module.
Yet another object of the invention is to provide such an RF transmitter which transmits a substantially constant energy pulse regardless of battery drainage.
These objects are realized in accordance with a broad aspect of the invention by a communication device including an RF transmitter mounted in conjunction with an IR transmitter allowing data to be transmitted by RF as well as by IR.